This invention relates to methods and apparatus for indicating the health status of removable memory systems, and in particular to displaying the health status of nonvolatile or flash or EEPROM type memory systems.
The use of non-volatile memory systems, such as flash memory storage systems, is increasing due to the compact physical size of such memory systems, and the ability for non-volatile memory to be repetitively reprogrammed. The compact physical size of flash memory storage systems facilitates the use of such storage systems in devices that are becoming increasingly prevalent. Devices which use flash memory storage systems include, but are not limited to, digital cameras, digital camcorders, digital music players, handheld personal computers, and global positioning devices.
Although non-volatile memory or, more specifically, non-volatile memory storage cells within flash memory systems may be repetitively programmed and erased, each cell or physical location may only be erased a certain number of times before the cell wears out. In some systems, a cell may be erased up to approximately ten thousand times before the cell is considered to be unusable. In other systems, a cell may be erased up to approximately one hundred thousand times or even up to a million times before the cell is considered to be worn out.
As nonvolatile memory is utilized, data is stored in the nonvolatile memory array, and data is also erased prior to use of the same locations, e.g., re-written. In most applications, nonvolatile memory is organized into blocks and when a write is initiated by a host that is coupled to the memory, generally through a controller device, one or more blocks are written at a time. Prior to re-writing the one or more blocks, such blocks are typically erased. When a particular block undergoes a certain threshold number of write and erase operations or cycles, this particular block will generally become defective or its ability to store information deteriorates.